Connection technology for the permanent connection of precast concrete elements
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What does this product have to offer?
With the BT-Spannschloss® (turnbuckle), precast concrete elements can be connected without any additional materials or aids.(Connecting concrete)
The connection can be fully loaded immediately without any curing times and therefore saves a considerable amount of time and money compared to other known systems.
Your advantages
- Dry screw connection without joint grouting, without special tools
- Immediately loadable, no curing times
- Weather-independent installation even at low temperatures or during precipitation
- Dismountable - dismantling of temporarily erected structures possible
- Three-point connection possible
- ETA with C2 classification - approved for the highest static and dynamic loads
Product details
The BT-Spannschloss® enables rational and precise assemblies as well as permanent connections of precast concrete elements. By using the BT-Spannschloss® and corresponding fasteners, precast elements can be joined together without a mineral grout. This eliminates curing times or downtimes due to low temperatures. The connection with the BT-Spannschloss® can be fully loaded immediately. You can watch the application of the BT-Spannschloss® in the product video.
The general technical approval (Z-14.4-599) and the European Technical Assessment (ETA 19/0013) certify the reliability of the product. The BT-Spannschloss® is offered in three sizes – M12, M16 and M20 – and is available in galvanised or stainless steel. On 12 March 2021, BT-Spannschloss® M12, M16 and M20 received the CE marking for use in the European Economic Area (EEA).
ETA with C2 classification
The BT-Spannschloss® (turnbuckle) has a European Technical Assessment (ETA) with classification C2. This means that the system is approved for applications with increased dynamic loads. The C2 classification includes higher load cycles and greater impact intensities than class C1 and thus extends the permissible range of applications.
360° view of the BT-Spannschloss® – M20
(Use the mouse to rotate the object or click here to open a new window).
Areas of application for BT-Spannschloss®
- Angle retaining walls in flood protection
- Residential and commercial construction
- Agricultural facilities (e.g. biogas plants, silos)
- Sewer and civil engineering (e.g. manholes, media channels, amphibian tunnels)
- Temporary structures
The BT clamping system can be used rationally and universally in a wide range of applications. For example, in the assembly and connection of angular supports and shaft elements in road construction and civil engineering, in construction measures in coastal protection areas, in ceiling and wall connections in residential and social construction and many other structural connections of precast concrete elements.
Note: The load capacity of the tensioning system depends largely on the type of anchor used. Several types of authorised anchor systems can be used according to the application requirements (please refer to the manufacturer’s data). In general, the load capacity of the turnbuckle is many times higher than that of the anchor systems.
BT-Spannschloss® - recess body
There is a matching recess body for each of the three sizes of the BT-Spannschloss®. The standard version of the recess body is made of polyethylene and has sloping sides for better stripping. It is possible to adapt the recess bodies in dimension or shape according to customer requirements.
The PE recess bodies are particularly robust and can therefore be reused many times. They enable a particularly stable positioning of the anchors and also ensure sufficient concrete cover for anchors and BT-Spannschloss®. For faster and more reliable application, the recess bodies can be equipped with magnets. Depending on the installation situation, however, it is also possible to screw or drill into the recess bodies if necessary.
Questions and answers about the product
1. what are the connection situations?
Basically, the BT-Spannschloss® can be used as butt joint, corner joint and three-point connection. Depending on the application, the type of recess in the precast concrete plant differs. Whereas the recess in the corner joint must be located as a whole in one element, the recess body can also be divided into two elements in the butt joint. For further information on the correct use of recess bodies, please contact your BT representative.
2. what does the system consist of?
The BT-Spannschloss® is available in three different sizes depending on your needs: M12, M16 and M20. In both the galvanised and stainless steel versions, the connection system consists of three essential components: the BT-Spannschloss®, the washers and the hexagon bolts.
3. what tolerances can the BT-Spannschloss® compensate for?
Dimensional tolerances of the joints and involved components are tolerable as long as the tensile force transfer of the anchor is guaranteed and the minimum screw-in depth of the screws is achieved.
4. how does the formation of the correct joint width work?
The joint widths can be varied by using different screws. The correct bolt combination can enable a regulation-compliant installation of the BT turnbuckle even with component tolerances. However, the minimum required and the maximum possible screw-in depth must always be observed.
5. is the BT-Spannschloss® corrosion protected and fire protection compliant?
Yes, the BT-Spannschloss® turnbuckle is corrosion-protected when installed in accordance with the approval. For particularly heavy chemical loads, the stainless steel version can also be used.
The BT-Spannschloss® turnbuckle is made of steel and complies with reaction to fire class A1 in accordance with Delegated Regulation (EU) 2016/364 and EN 13501-1.
As part of a fire test on a hybrid ceiling, in which the turnbuckle was used as a ring anchor, a fire resistance period of 90 minutes was demonstrated. Further results from fire protection tests can be obtained from your BT contact person.
6. What are the minimum wall thicknesses for the BT-Spannschloss®?
The required minimum wall thickness depends on the respective thread size of the BT-Spannschloss®. Please note the following specifications:
M12: Minimum wall thickness 100 mm
M16: Minimum wall thickness 120 mm
M20: Minimum wall thickness 140 mm
These values ensure that the loads can be properly absorbed and transmitted. For deviating applications or special solutions, please contact our technical support.
7. What does the C2 classification of the ETA mean for the BT-Spannschloss® ?
The C2 classification confirms the suitability of the BT-Spannschloss® for applications with increased dynamic loads. Compared to class C1, higher load cycles and greater action intensities are taken into account. This is based on the assessment in accordance with the EAD as part of the ETA.
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Your contact
Mohammad Afa Alrefaie
Phone: +49 391 7352 41
